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Simulators for training and validation of image-guided procedures

Erik Fosse
1 January, 2008  

Erik Fosse
MD PhD
Professor
The Interventional Centre Rikshospitalet
University of Oslo
Norway

Most invasive treatments in hospitals today are carried out through some kind of image ­guidance. Advances in image guidance and in instruments make minimally invasive, image-guided ­approaches ­possible where before major open surgery was the only option. In the last 20 years, laparoscopic surgery has moved from cholecystectomy, appendectomy and fundoplication to ­major ­procedures such as colon resection, liver resection, pancreas resection, living donor ­kidney harvest and total prostatectomy. In the chest, thoracoscopic treatment of recurrent ­pneumothorax, ­sympathectomy and lung wedge resection for metastasis were introduced in the 1990s. Anatomical lung resection and minimally invasive coronary and valve surgery are also fairly common. For most of these ­procedures, ­robotic telemanipulation of the instruments has been tried. Today robotic total prostatectomy is a ­common procedure.

Image-guided surgery differs greatly from open techniques, where, in most cases, the surgeon looks at a two-dimensional screen; in addition, in the case of open techniques, the instruments are longer and even a little bleeding can impede visualisation. Many surgeons experience difficulties in spatial orientation, and even skilled surgeons cannot always fully overcome this problem.

Thus, there is an obvious need for training, and there may also be a need for surgeon ­selection and certification. Training in laparoscopic surgery often involves live animal surgery. To reduce animal training, box trainers and, eventually, virtual-reality (VR) simulators were introduced. Today most training centres for endoscopic surgery and intervention offer training on a whole range of VR simulators.

Training techniques
There are currently three options for training. The box trainer, in which animal organs are mounted, is still widely used, with the surgeon performing laparoscopic surgery on these organs. The advantage of this technique is that the surgeon works with real laparoscopic instruments, including both camera and ­surgical equipment, and haptic feedback is the same as during real surgery. The disadvantage of using the box trainer is that organs have first to be acquired, and then mounted professionally. It is also difficult, with this technique, to define standardised training sessions with precise metrics for assessment and certification.

To develop an easier and more systematic training approach, the first VR simulators were introduced in the 1990s. At first, graphics and tissue simulation were of poor quality and training consisted of ­working on abstract figures (ie, moving or cutting off the edges of cubes and triangles). ­Gradually, the simulators had better graphics, giving more vivid images. In the past few years, systems have ­improved ­considerably, and it is now possible to integrate computed tomography (CT) and magnetic resonance imaging (MRI) ­volumes of real pathologies into the simulators. The advantage of the VR simulators is that there is no need to mount organs, as both instruments and organs are virtual. VR simulators are fully digitalised systems, allowing both training and validation of skills; therefore, they can offer a pedagogic platform in which trainees can have a good idea of improvement in their skills.

The third training option is a hybrid system in which a digital system is linked to a box ­trainer. Skills can be monitored in the same way as with VR simulators, with the haptic feedback, experience of ­working with real laparoscopic instruments and excellent graphics of real anatomy laparoscopic instruments from the box trainer. The hybrid system, however, requires the mounting of organs in the box, and does not offer the same potential for measuring tissue and instrument behaviour as VR simulators.

In collaboration with SimSurgery (see Resources), we developed a simulator program for robotic ­vessel anastomosis that equalled real-time surgery in training effect. To validate the simulated ­training, we compared the suturing skills acquired through VR training and those acquired using a robotic ­system; the same skills were gained using one technique or the other.(1) One of the main complaints with VR ­trainers is the lack of haptic feedback and the fact that real instruments are not being used. When surgery is performed robotically, haptic feedback is also lacking and there is no direct contact with laparoscopic instruments. VR training is therefore ideal for robotic surgery.

[[HHE07_fig1_T46]]

Radiology-guided interventions
Interventional radiology is one of the fastest-expanding fields of medicine. A number of advanced ­radiology-guided interventions have been developed in angiography rooms. Percutaneous cardiac ­interventions in coronary arteries are one of the most common procedures in university hospitals today. These image-guided procedures, which require different skills than those necessary for open surgery, enable cardio‑logists and radiologists to perform image-guided surgical interventions. Cardiologists and radiologists ­acquire skills in catheter handling through performing diagnostic procedures. In the past few years, ­however, noninvasive imaging modalities such as CT and MRI have increasingly been used in ­vascular diagnostics. Angiographic diagnostic imaging is becoming rare in neuroradiology; thus, ­radiologists and, eventually, cardiologists will loose the training provided by interventional diagnostics. Therefore, training through the use of simulators has increased in interventional radiology and ­cardiology. These simulators use real fluoroscopic images, and simulators for radiological interventions now provide images much closer to reality. These simulators also monitor the skills of the ­interventionist, such as optimal catheter handling and optimal balloon placement.

It is now common for companies to deliver a new implant system at the same time as the VR ­training program. In future, it can be assumed that simulator-based certification and accreditation will be mandatory before healthcare workers can start using new tools and techniques.

Validation of skills
There are no objective means of validating a surgeon’s skills, the only “validation” available being ­patient outcome after surgery. VR simulators not only train but also monitor technical competences. Skills monitoring­ systems vary from one program to another, but they all contain a system for validating skills by logging the number of attempts to perform a task, the number of movements, etc. These ­programs also provide the surgeon with a self-evaluation system. There is evidence that skills acquired on VR simulators for endoscopic and laparoscopic procedures can be transferred, to improve performance during real operations. However, more studies are needed to demonstrate the true predictive validity of the skills monitoring systems included in VR simulators for real surgical or interventional procedures. In addition, there is currently no common platform and training curriculum.

[[HHE07_fig2_T47]]

[[HHE07_fig3_T47]]

There is a potential for VR simulators to provide objective assessment of competences, which could be used in a certification process. In the future, simulations will no doubt be incorporated in the certification process for both laparoscopic surgery and interventional radiology. VR evaluation is already incorporated in the examination process in laparoscopic training centres. The challenge in using a VR simulator for accreditation and certification is that it needs to provide a uniform, robust platform, with an agreed set of tasks that need to be completed.

Today each simulator company provides its own system. A common set of procedures, skills set and metrics should ideally be used in all simulators, thereby providing a true evaluation of the ­candidate. These common demands should ideally be developed by national and international certification boards. Simulator training and validation have become issues for all international organisations to ­address. The European Association for Endoscopic Surgery (EAES) has established a Work Group for Evaluation and Implementation of Simulators and Skills Training, which has already evaluated ­different simulators and is currently discussing validation.(2) The Society of American Gastrointestinal and Endoscopic Surgeons has integrated simulator ­training in its framework for post-residency surgical education and training guidelines. The ­Cardiovascular and Interventional Radiological Society (CIRSE), the Society of Interventional Radiology (SIR) and the ­Radiological Society of North America (RSNA) have established individual medical simulation task ­forces, as well as a common task force, to establish uniformity in simulation validation.(3)

Conclusion
Virtual-reality simulation offers a way of testing out new procedures and training surgeons and interventionists in a safe and simple way. As the complexity of procedures increases and new techniques and technologies are introduced in healthcare, the need for structured training and certification increases. Although the VR systems offer this possibility, development and consensus are needed for a uniform ­accreditation and certification system.

References

  1. Halvorsen FH, Elle OJ, Dalinin VV, et al. Virtual reality simulator training equals ­mechanical robotic training in ­improving robot-assisted basic suturing skills Surg Endosc 2006;20(10):1565-9.
  2. Carter FJ, Schijven MP, Aggarwal R, et al; Work Group for Evaluation and ­Implementation of Simulators and Skills Training Programmes. Consensus guidelines for validation of virtual reality surgical simulators. Surg Endosc 2005;19(12):1523-2.
  3. Gould DA, Reekers JA, Kessel DO, et al. Simulation devices in interventional radiology: validation pending. J Vasc Interv Radiol 2006;17(2 Pt1):215-6.

Resources
European Association of Endoscopic Surgery (EAES) Work Group for Evaluation and ­Implementation of ­Simulators and Skills Training
W: www.eaes-eur.org
Society of American
Gastrointestinal and Endoscopic surgeons (SAGES) framework for post-residency surgical education and training guidelines
W: www.sages.org
Cardiovascular and Interventional radiological society (CIRSE) task force
W: www.cirse.org
Society of Interventional Radiology (SIR) task force
W: www.sirweb.org
Radiological Society for North America (RSNA) Task Force
W: www.rsna.org
SimSurgery, Norway.
W: www.simsurgery.com
Mentice
W: www.mentice.com